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Flexural behaviour of steel beams with double corrugated webs: Experimental and analytical investigations
Full text linkCorrugated web steel beams (CWSBs) have been widely used in engineering structures due to the benefits of light weight and superior bearing capacity. Normally, traditional CWSBs where prefabricated floor slabs are installed on the top flange of the steel beams, resulting in the reduction of ceiling height, and increasing waste of available space and material. In view of this, an innovative steel beam with double corrugated webs (SBDCW) which can be applied in ordinary frame and heavy-duty frame structures, was developed to solve the above typical limitations for conventional CWSB structures. To investigate the effect of thin-walled corrugated steel webs (TCSWs) on the flexural of SBDCWs, flexural tests of seven specimens while varying the critical parameters were conducted to reveal the failure modes of SBDCWs and collaborative work mechanism between TCSWs and flanges. The test results showed that there was a shear lag effect in steel flanges, and the accordion effect of TCSWs was observed based on the strain analysis of web. Subsequently, a finite element model was developed and a parameter study was also conducted to further evaluate the influences of web thickness, web angle and beam height on the flexural behavior of SBDCWs. Furthermore, an analytical method for predicting the ultimate flexural capacity of SBDCWs was proposed fully taking into account the shear lag effect of flanges, contribution and accordion effect of TCSWs. The calculated results were in good agreement with the test and FEA values, indicating that the proposed methods can accurately predict ultimate flexural capacity of SBDCWs. In summary, this research can provide references and foundations for the design, investigation and application of thin-walled CWSBs in ordinary and heavy-duty frame structures
Magnesium in the Critically Ill Patient
Full text linkMagnesium is an essential electrolyte, being the second most abundant intracellular cation and having many physiologic functions in the body.1 It is an essential cofactor for many enzymes, including Na-K-ATPase, calcium ATPase, cyclases (eg, adenylyl cyclase, guanylyl cyclase), protein kinases, DNA and RNA polymerases, and is vital for protein and DNA synthesis, carbohydrate metabolism, cell signaling, immune modulation, and coagulation. Because of its role as a calcium antagonist, magnesium also alters electrophysiological properties of cells and hence influences membrane resting potentials, neurotransmitter release, cell excitability, and muscle contractility.4 Magnesium-mediated inhibition of calcium ion currents in vascular smooth muscle has vasodilatory effects because of L-type calcium channel inhibition (and hence decreased activity of calmodulin-dependent myosin light chain kinase), modulation of intracellular cell signaling, and activation of the sarcoplasmic/endoplasmic reticular Ca2+ATPase resulting in calcium sequestration
Process Modelling, Simulation and Technoeconomic Evaluation of Batch vs. Continuous Pharmaceutical Manufacturing (CPM) of Cephalexin
No full textCost-effective antibiotics production is essential in the fight against antimicrobial resistance, since pharmaceutical companies must frequently abandon their antibiotics research due to: (i) high research and development (R&D) costs, (ii) increasingly stringent environmental regulations, and (iii) government initiatives aimed at curbing antimicrobial resistance by restricting use of new antibiotic products. Consequently, in-silico process design can be effectively employed to reduce the manufacturing cost of new and existing antibiotics whilst simultaneously accelerating their development and improving their affordability. The present paper examines how process modelling and technoeconomic evaluation can be used to guide the design of fully aqueous and aqueous two-phase system (ATPS) manufacturing platforms for the production of cephalexin, a generic cephalosporin antibiotic. Moreover, detailed comparisons of batch vs. continuous pharmaceutical manufacturing (CPM) for the ATPS protocol illustrate key benefits.</p
Experimental and Numerical Investigation of Micro/Mini Channel Flow Boiling with a Self-Rewetting Fluid at different Flow Inclinations
No full textFlow boiling of a self-rewetting fluid (SRF) in high aspect ratio microchannels was investigated experimentally at various applied heat fluxes, and supported with numerical simulations to provide small scale insight into the thin film liquid regions. A 5% v/v 1-butanol-water mixture was used as the SRF and was compared to pure water. The microchannel had an aspect ratio of 20 (6 mm width by 0.3 mm height) and a length of 70 mm and received one-sided heating. Experimental work considered sub-cooled liquid inlet conditions for five channel inclination angles ranging from -90° (downward flow) to 90° (upward flow) at mass fluxes of 10, 15 and 25 kg/m2s. It was observed that the flow inclination severely affected the vapour liquid distribution in the channel and the heat transfer performance. Upward flow had better heat transfer performances than downward flow. Compared to water, the SRF had a similar heat transfer performance for horizontal flow, but outperformed the water for downward flow to such an extent that the SRF exhibited a steady robust boiling mechanism while water almost instantly resulted in severe dry-out at the top (inlet) of the channel. Further insight was obtained via a series of two-dimensional numerical simulation at a mass flux of 15 kg/m2s. It was found and shown via velocity vectors that the unique surface tension properties of the SRF meant that the surrounding fluid was drawn into the heated region, as explained by the Marangoni effect, allowing for a continually wetted surface, and thus enables continued boiling to occur. Numerically it was found, compared to the water, that for the SRF the surrounding fluid flow resulted in reduced bubble growth rates, as well as thicker liquid film layers between the bubble and heated wall
A relation between the Dirichlet and the Regularity problem for Parabolic equations
No full textWe study the relationship between the Dirichlet and Regularity problem for parabolic operators of the form L=div(A∇⋅)−∂ t on cylindrical domains Ω=O×R, where the base O⊂R n is a uniform domain with n−1 Ahlfors regular boundary (and for one result a Lipschitz domain) in the spatial variables. In the paper we answer the question when the solvability of the L p Regularity problem for L (denoted by (RL) p) can be deduced from the solvability of the L p ′ Dirichlet problem for the adjoint operator L ⁎ (denoted (DL⁎) p ′ ). We show that this holds if for at least one q∈(1,∞) the problem (RL) q is solvable. That is, we establish a duality/dichotomy result: Dirichlet solvability implies Regularity solvability in the dual L p range, or the Regularity problem is not solvable in any L p. Results like these were only known in the elliptic settings (Kenig-Pipher (1993) and Shen (2006)) but are new for parabolic PDEs. Our result is one of the key components needed for the recent advancement of Dindoš, Li and Pipher in understanding solvability of the Regularity problem for operators whose coefficients satisfy certain natural Carleson condition (called also DKP-condition in the elliptic case).</p
Stochastic modelling of burden of livestock diseases on domestic ruminants in Ethiopia
No full textThis study, carried out in 2022-2023, quantified the financial burden of disease in cattle, sheep and goats in Ethiopia for the year 2021 using the animal health loss envelope (AHLE) metric. The AHLE measures all cause disease burden, avoidable and non-avoidable, as the difference in the financial performance of a livestock production system (e.g., gross margin) comparing a scenario where animals are in an ideal state of health to the current situation. A stochastic dynamic population model (DPM) was employed to calculate the gross margin for an average farm and for the national herd under these current and ideal health scenarios. Data for parametrizing the DPM were derived from secondary sources and expert elicitation. The stochastic DPM was simulated for 10,000 iterations and results are reported as means with 95 % percentile intervals (PI). The annual AHLE per average farm was estimated at USD 1209 (95 %PI:392-2470) in cattle, USD 158 (95 %PI:66-292) in sheep and USD 416 (95 %PI:136-847) in goats. At national level, the annual AHLE in ruminants was USD 18.39 billion with USD 15.42 billion (95 % PI:12.70-18.57) in cattle, USD 1.04 billion (95 % PI:0.84-1.30) in sheep, and USD 1.93 billion (95 % PI:1.64-2.25) in goats. Morbidity losses constituted the largest component of the AHLE, exceeding 50 % across all species, while animal health expenditure represented the smallest component, accounting for less than 2 % of AHLE in all species. This high disease burden, with minimal contribution from animal health expenditure, indicates significant opportunity for improvement through investment in animal health.</p
Localised variants of multilinear restriction
Full text linkWe revisit certain localised variants of the Bennett-Carbery-Tao multilinear restriction theorem, recently proved by Bejenaru. We give a new proof of Bejenaru's theorem, relating the estimates to the theory of Kakeya-Brascamp-Lieb inequalities. Moreover, the new proof allows for a substantial generalisation, exploiting the full power of the Kakeya-Brascamp-Lieb theory
Parental use of distraction and portioning to reduce snack intake by children with avid eating behaviour:An experimental laboratory study
Full text linkIntroduction: Children's avid eating behaviour is characterised by frequent snacking and food responsiveness. Parents need evidence-based advice on specific feeding practices, such as distraction techniques and portioning, that can be used to reduce children's intake of high energy-dense snacks. This experimental laboratory study tested the effectiveness of these feeding practices. Methods: Parents and children (3–5 years; N = 129) who were identified as having an avid or typical eating profile were recruited and randomly allocated to one of three conditions. Following a standardised meal, children's energy intake (kcal) in the absence of hunger was assessed. While children had access to a snack buffet, parents were asked to use one of the following feeding practices: (1) Distract – using distraction techniques to delay children's snack intake; (2) Portion – allowing children to have snacks from pre-portioned pots; or (3) Control – allowing children to eat the type and number of snacks that their child wanted to. Results: Children in the distraction condition consumed significantly less energy from snacks (M = 54.44 kcal, SD = 73.30) compared to children in the portion (M = 103.89 kcal, SD = 91.33, p < .001) or control condition (M = 115.92 kcal, SD = 90.55, p < .001). Energy intake in the portion and control conditions was not significantly different (p > .05). Children with avid versus typical eating profiles did not differ significantly in energy intake (p > .05). Conclusion: Parental use of distraction techniques may be effective for reducing children's intake of high energy-dense snacks and could be recommended for use to support the development of children's healthy eating. Research to examine the effectiveness of distraction in real-world settings is now needed.</p
Predicting words across languages depends on language context:Evidence from visual world eye-tracking
No full textThere is good evidence that monolingual comprehenders can predict the form of upcoming words, and also that bilinguals often activate words from both languages in parallel during bottom-up language comprehension. But it is unclear whether bilinguals predict the form of upcoming words in the language that they are not hearing, and whether such predictions depend on whether or not they have recently encountered that language. We investigated these questions in two visual-world eye-tracking experiments by asking whether Mandarin Chinese (L1)-English (L2) bilinguals pre-activate Mandarin phonological representations of predictable words during English comprehension. Participants heard English sentences containing a highly predictable word while viewing a display. They fixated more on a competitor object whose Mandarin name was a homophone of the Mandarin translation of the predictable word than an unrelated object when both languages were used (Experiment 2) but not when just English was used (Experiment 1). Our findings suggest that bilinguals predict across languages when both languages are contextually relevant but not otherwise
Optimal placement of electric vehicle slow-charging stations: A continuous facility location problem under uncertainty
Full text linkElectric vehicles (EVs) are becoming a key mechanism to reduce emissions in the transportation industry, and hence contribute to the green transition. In this paper, we present a mathematical programming model which determines the optimal placement of EV charging stations such that chargers are placed in the most cost-efficient way possible for all stakeholders, assuming additionally that EV charging demand is inherently stochastic in nature. The model is formulated as a two-stage, continuous location–allocation model in the form of a generalised Weber problem in two dimensions. However, this formulation is non-convex and notoriously difficult to solve. We therefore propose a suitable discretisation procedure to find high quality solutions in suitable time. The discretisation procedure shows strong performance across a variety of computational experiments using randomly generated scenarios, maintaining robustness in terms of the objective value and overall solution quality.A part of this solution procedure was entered into the 15th AIMMS-MOPTA Optimisation Modelling Competition
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